Spark-plug testing and indicating device



May 27, 1924.

E. M. PLUMMER SPARK PLUG TESTING AND INDICATING DEVICE Filed March 17 1921 INVENTOR Earl M. Ellummer.

WITNESSES A ITO/M1578 I 1 1,495,43 FIE.

nan-L MARVIN PLUMMER, or CHICAGO, rumors.

SPARK-PLUG TESTING AND INDICATING DEVICE.

' Application filed fiarch 17, 1921. Seria1 No. 453,107.

To all whom it may 00mm."

Be it known that I, EARL M. PLUMMER,

a citizen of the United States, and a resident tion and adapted to receive the threaded terminal posts 21. Each post is provided with a knurled nut, 22, so that the same may of Chicago, inthe county'of Cook and State \be locked in adjusted position. Also each of Illinois, have invented certain new and useful Improvements in Spark-Plug Testing and Indicating following is a'specification- This invention. relates to a spark plugtesting and indicating device.

The object of the invention is to provide such a device, whereby the functioning or condition of each of the s ark plugs of an enginemay be continuous y indicated. It is also an object of the invention that in case any spark plug becomes fouled or otherwise inoperative an alarm will indicate such condition.

The invention is particularly adapted for use in connection with an automobile and so illustrated in the accompanying drawings, in which: a

- Figure 1 is a top plan View of the housing and supporting means for the spark gap terminals, 1 Y

Figure 2 is an end elevation of the box or'housing shown in Figure 1,

Figure 3 is a transverse section of the box or housing shown in Figure 1,

Figure 4 is a. diagrammatic view illustrating the preferred embodiment ofv my invention, and

Figure 5 is a detailed view of the auxiliary spark terminals.

Referring to Figure 4 more particularly, 10 indicates a battery which is grounded on its one side as at 11. The other side of this battery is led to one end of the primary windin of the induction coil 12, and the other side of said coil is grounded as indicated at 13. One side of the secondary of the coil 12 is connected in the usual manner to the distributing box 14, and its other side grounded as at 14'. -The. distributing box has extending therefrom a lead 15 for each of the spark plugs 16 which in this instance are four in number.

Referring to Figure 1 the box or housing generally indicated by the reference letter A comprises a rear wall 17, the top and bottom walls 18 and the front wall 19 which is preferably of glass as shown. Mounted.

within the box is a substantially U-shaped member 20. The horizontal portions of this U-shaped member are provided with threaded openings in equally spaced rela- Devices, of which the v of these posts has a slotted head as indicated at 23 for accommodating a screw driver in adjustment. These terminal posts are provlded in pairs as shown and each pair represents an openingor spark gap in the circult of each spark plug 16. As illustrated in Figure 4 the circuit of each spark plug comprises a lead- 15 which extends from the distributing box 14 to a terminal of one of the: pairs of the spark gap terminals 22 and also the lead 24 which connects the other termlnal of said pair with its respective spark plug 16. Each spark plug is grounded as at 25 to the frame of the engine in the usual manner,which completes the circuit to the secondary of the induction coil 12.

An auxiliary spark terminal is provided for each pair of terminals 22. This auxil- 1ary spark terminal is particularly illustrated in Figure 5, and comprises an elongated, portion 25 on each side of which'there is formed an angular projection 26. The

- elongated portion 26 is also provided with an opening adapted to receive the terminal posts 21. These auxilia spark terminals are mounted as shown in igure 1 and held in position by the knurled nuts 22. The forward end may be bent downwardly as at 28 to moresecurely hold the same in position. As is obvious, the end auxiliary spark terminals need only have a projection 26 on the inner side thereof.

- It also may here be pointed out that the top or cover of the box A may be removable and secured in position'by means of screws or the like as indicated at 29; and that the rear wall 17 may be suitably secured to the instrument board of the automobile.

In the operation of. the present apparatus,

if the spark plugs 16 are properly-functioning the passage of the spark between the pairs of terminals 21 will be intermittent and regular, butin case a spark plug circuit is opened or otherwise offers a great resistance to the passage of the current, the j umping of the-spark between the pair of termiplug which is in good condition. A spark jumping between adjacent auxiliary spark terminals would produce a cracking sound of an irregular character and attract the attention of the driver or operator of the auto mobile and hence he would immediately become aware that the defective spark plug needed attention. In this manner the particular spark plug which is out of order isindicated to the driver.

As long as the passage of the sparks between the spark gap created by each pair of spark terminals 21 is regular and intermittent, the driver will know that the spark plugs are functioning properly.

While l have shown and described this invention when used in connection with an automobile engine it is to be understood that the same could be equally used with any type of engine serving any purpose.

ll claim:

1. In a device of the character described, a member made of insulating material, a plurality of spark terminals carried by said member and arranged in pairs, and auxiliary spark points carried by said terminals and adapted to establish spark gaps between adjacent terminals.

2. In an ignition apparatus a pair of spaced conduetors,' earl coinhu'tor being adapted to be included in a high potential circuit of the ignition apparatus, and a projection extending from each conductor adapted to establish a spark gap between the free ends thereot.

EARL Matti llN PLUMMER. 

